危地马拉高档绿色翡翠的矿物组成及成因  

Mineral Component and Genesis of High-Grade Green Jadeite Jade from Guatemala

作　　者：王礼胜 张海衡 刘静怡 王露丝 欧阳秋眉 柳东明 刘伟 WANG Lisheng;ZHANG Haiheng;LIU Jingyi;WANG Lusi;OUYANG Qiumei;LIU Dongming;LIU Wei(International Jadeite Jade Institute,Hebei GEO University,Shijiazhuang 050031,China;School of the Earth Science,Hebei GEO University,Shijiazhuang 050031,China;Gemmological Testing Center,Hebei GEO University,Shijiazhuang 050031,China;Hongkong Gemmological Institute,Hongkong,China)

机构地区：[1]河北地质大学国际翡翠研究院,河北石家庄050031 [2]河北地质大学地球科学学院,河北石家庄050031 [3]河北地质大学珠宝检测中心,河北石家庄050031 [4]香港珠宝学院,中国香港

出　　处：《宝石和宝石学杂志（中英文）》2022年第5期11-30,共20页Journal of Gems & Gemmology

基　　金：河北省科技厅提供“珠宝与矿物岩石材料科技创新创业服务基地”项目资助。

摘　　要：选取危地马拉高档绿色翡翠样品为研究对象,采用宝石显微镜、偏反光显微镜、激光显微拉曼光谱仪和电子探针仪等测试手段,开展了翡翠样品的外观特征、放大观察、组成矿物、显微结构、拉曼光谱及矿物化学成分研究。根据矿物组成及其演化,将成矿作用分为三期:(1)早期成矿作用产物为具粗粒、半自形-自形粒柱状结构的硬玉,化学成分很纯;(2)主成矿期以交代作用为主,早阶段形成的产物为颗粒细小的硬玉,与第一期的硬玉相比含有相对较高的FeO、Cr_(2) O_(3)、MgO和CaO含量,晚阶段形成的产物为颗粒细小的绿辉石,MgO和CaO含量高,因Cr_(2) O_(3)含量具规律性变化而相应呈深浅不同的绿色;(3)晚期成矿作用产物为硬玉(或钠长石)+榍石等,呈充填结构,榍石呈网脉状分布于硬玉、绿辉石颗粒之间或微裂隙中。晚期的硬玉(钠长石)+榍石+流体包裹体组合,即翡翠中的白色棉状物,实际上是一类流体熔融包裹体。流体熔融包裹体中的流体相,含有CO_(2)、CO等成分,其中2145 cm^(-1)处的特征拉曼位移峰最强、指示着CO含量很高的强还原成矿环境,这与样品中普遍存在无定型碳相印证。结果显示,所研究大多数危地马拉高档绿色翡翠样品的矿物组成以硬玉为主或硬玉是其主要矿物之一,白色棉状物中普遍出现的“晚期硬玉+网脉状榍石+以CO为主的流体包裹体”的组合,可以作为危地马拉高档绿色翡翠与缅甸绿色翡翠鉴别的重要参考特征。High-grade green jadeite jade samples from Guatemala were selected as the research objects.Gem microscope,polarizing microscope,microscopic laser Raman spectrometer and electron probe microanalyser,etc.,were used to carry out the analysis on the appearance characteristics,magnification observation,constituent minerals,microstructures,Raman spectra,mineral chemical compositions of the samples.According to the constituent minerals and their evolution,3 periods of mineralization were observed:The product of early mineralization period is jadeite with coarse-grained,hypautomorphic-automorphic granular-columnar texture,and their chemical compositions are very pure;The main mineralization period is metasomatism,in which the product formed in the earlier period is fine-grained jadeite with relatively higher content of FeO,Cr_(2) O_(3),MgO and CaO than that of jadeite formed in early mineralization period,and the product formed in the later period is fine-grained omphacite which contains high content of MgO and CaO,the shades of green of which vary correspondingly to regular variations of Cr_(2) O_(3) content;The products of late mineralization period are jadeite(or albite)+titanite,etc.in filling texture,where titanite is mainly distributed in reticulated veins between jadeite/omphacite particles or in microfractures.The combination of jadeite(or albite)+titanite+fluid inclusions formed in the late period,which appear as the white cotton-like substance in the jadeite jade,is actually a type of fluid-melt inclusions.The fluid phase in the fluid-melt inclusions contains CO_(2) and CO etc.,and the 2145 cm^(-1) characteristic Raman shift peak is the strongest,indicating a h ighly reductive forming environment with high CO content,which is corroborated by the amorphous carbon generally observable in the samples.Jadeite is the main mineral or one of the main minerals in most of the high-grade Guatemalan green jadeite jade samples studied.In high-grade green jadeite jades,the late period combination of jadeite+reticulated tita

关 键 词：翡翠 硬玉 绿辉石 榍石 危地马拉 缅甸 

分 类 号：TS93[轻工技术与工程]